Vegas shooter on anti-anxiety meds:autopsy

An autopsy has done nothing to help explain the motive of Las Vegas gunman Stephen Paddock (File).

The autopsy report on Las Vegas gunman Stephen Paddock does nothing to help explain why he carried out the deadliest shooting in modern US history - his body did not hold diseases or drugs or other substances that could have caused aggressive behaviour.

In fact, it showed he was a sober, healthy 64-year-old.

The report - released on Friday in response to a lawsuit by the Associated Press and the Las Vegas Review-Journal - shows gunman Stephen Paddock had anti-anxiety drugs in his system but was not under the influence of them.

Paddock unleashed a barrage of bullets from his high-rise hotel suite into a crowd at a country music festival below, killing 58 people and injuring more than 800 others on October 1.

He fatally shot himself before officers stormed his suite.

The autopsy showed the 1.8m Paddock was slightly overweight at 102kg, had high blood pressure and bad teeth. However, nothing was unusual in his physical condition.

His cremated remains were released to his brother in January.

Paddock's motive has been a mystery since he opened fire from the 32nd floor of the Mandalay Bay casino-hotel.

A preliminary report released last month by Las Vegas police says the high-stakes gambler had been on a losing streak, was obsessed with cleanliness, possibly bipolar and was having difficulties with his live-in girlfriend.

Investigators believe Paddock acted alone and he did not leave a note or manifesto before he was found dead in the room.

Police found 23 rifles and a handgun in his suite, with some rifles fitted to fire like fully automatic weapons.

His live-in girlfriend, Marilou Danley, told investigators that Paddock had become "distant" in the year before the shooting, according to the preliminary report.